如何防止Jsoup拋出http錯誤的異常？

Question

我正在使用Jsoup來製作應用程序，它將獲取有關公共交通卡現金餘額的信息。但是如果用戶輸入錯誤的卡號和我的應用程序發送給網站，服務器將發送http錯誤409，並輸出該卡號不存在。我設法寫的代碼這個簡單的和平：

if (res1.statusCode() == 200) { 
    doc1 = res1.parse(); 
    answer = doc1.body(); 
    title = answer.text(); 
} else if (res1.statusCode() == 409) { 
    title = "Neteisingas kortelės numeris arba nepavyko patikrinti"; 
} 

哪個寫一些東西到String title，因爲如果沒有這個解決方案，它留給title空，從而導致字符串標記異常的代碼另一部分。 畢竟這個問題來了如何防止Jsoup拋出異常？

我的例外：

07-27 23:30:12.831 22409-22427/com.bjobs.vvtcards W/System.err: org.jsoup.HttpStatusException: HTTP error fetching URL. Status=409, URL=https://mano.vilniustransport.lt/card/card-check?number=1231234566&_csrf_token=ke_q5dOIIzHCIB5OsuS-N6MlSLXh-im78brCfYn631c 
07-27 23:30:12.831 22409-22427/com.bjobs.vvtcards W/System.err:  at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:682) 
07-27 23:30:12.831 22409-22427/com.bjobs.vvtcards W/System.err:  at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:629) 
07-27 23:30:12.831 22409-22427/com.bjobs.vvtcards W/System.err:  at org.jsoup.helper.HttpConnection.execute(HttpConnection.java:261) 
07-27 23:30:12.832 22409-22427/com.bjobs.vvtcards W/System.err:  at com.bjobs.vvtcards.MainActivity$2.run(MainActivity.java:183) 
07-27 23:30:12.832 22409-22427/com.bjobs.vvtcards W/System.err:  at java.lang.Thread.run(Thread.java:761) 

和全Jsoup代碼，如果你需要它：

try { 
       res = Jsoup.connect("https://mano.vilniustransport.lt/login") 
         .userAgent("Mozilla/5.0 (Linux; Android 7.1.1; LG-D855 Build/NOF26W) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.83 Mobile Safari/537.36") 
         .ignoreHttpErrors(true) 
         .method(Connection.Method.GET) 
         .execute(); 
       doc = res.parse(); 
       Map welcomeCookies = res.cookies(); 
       Element inputHidden = doc.select("input").last(); 
       //String securityTokenKey = inputHidden.attr("name"); 
       String securityTokenValue = inputHidden.attr("value"); 
       for (int i = 0; i < cycleCounter; i++) { 
        String fullData = cardsNids.get(i); 
        String[] split = fullData.split("\n"); 
        String cardNu = split[1]; 
        Connection.Response res1 = Jsoup.connect("https://mano.vilniustransport.lt/card/card-check?number=" + cardNu + "&_csrf_token=" + securityTokenValue) 
          .header("Content-Type", "text/html; charset=UTF-8") 
          .userAgent("Mozilla/5.0 (Linux; Android 7.1.1; LG-D855 Build/NOF26W) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.83 Mobile Safari/537.36") 
          .cookies(welcomeCookies) 
          .execute(); 
        if (res1.statusCode() == 200) { 
         doc1 = res1.parse(); 
         answer = doc1.body(); 
         title = answer.text(); 
        } else if (res1.statusCode() == 409) { 
         title = "Neteisingas kortelės numeris arba nepavyko patikrinti"; 
        } 
        String presentData = cardsNids.get(i); 
        cardsNids.set(i, presentData + "\n" + title); 
       } 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 

更新代碼：

private void checkBalance() { 
    new Thread(new Runnable() { 
     @Override 
     public void run() { 
      try { 
       res = Jsoup.connect("https://mano.vilniustransport.lt/login") 
         .userAgent("Mozilla/5.0 (Linux; Android 7.1.1; LG-D855 Build/NOF26W) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.83 Mobile Safari/537.36") 
         .ignoreHttpErrors(true) 
         .method(Connection.Method.GET) 
         .execute(); 
       doc = res.parse(); 
       Map welcomeCookies = res.cookies(); 
       Element inputHidden = doc.select("input").last(); 
       //String securityTokenKey = inputHidden.attr("name"); 
       String securityTokenValue = inputHidden.attr("value"); 
       for (int i = 0; i < cycleCounter; i++) { 
        String fullData = cardsNids.get(i); 
        String[] split = fullData.split("\n"); 
        String cardNu = split[1]; 
        res1 = Jsoup.connect("https://mano.vilniustransport.lt/card/card-check?number=" + cardNu + "&_csrf_token=" + securityTokenValue) 
          .header("Content-Type", "text/html; charset=UTF-8") 
          .userAgent("Mozilla/5.0 (Linux; Android 7.1.1; LG-D855 Build/NOF26W) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.83 Mobile Safari/537.36") 
          .cookies(welcomeCookies) 
          .execute(); 

         doc1 = res1.parse(); 
         answer = doc1.body(); 
         title = answer.text(); 
        String presentData = cardsNids.get(i); 
        cardsNids.set(i, presentData + "\n" + title); 
       } 
      } catch (HttpStatusException e) { 
       if (res1.statusCode() == 409) { 
        title = "Neteisingas kortelės numeris arba nepavyko patikrinti"; 
       } 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 

      // Update the progress bar 
      mHandler.post(new Runnable() { 
       public void run() { 
        adapter = new RecyclerAdapter(createList(cardsNids.size())); 
        recyclerView.setAdapter(adapter); 
       } 
      }); 
     } 
    }).start(); 
} 

而現在即時得到另一錯誤：

07-28 20:56:51.328 21205-21242/com.bjobs.vvtcards E/AndroidRuntime: FATAL EXCEPTION: Thread-4 
                    Process: com.bjobs.vvtcards, PID: 21205 
                    java.lang.NullPointerException: Attempt to invoke interface method 'int org.jsoup.Connection$Response.statusCode()' on a null object reference 
                     at com.bjobs.vvtcards.MainActivity$2.run(MainActivity.java:194) 
                     at java.lang.Thread.run(Thread.java:761) 

Answer 1

試試這個：

catch (HttpStatusException e) { 
    if (res1 != null && res1.statusCode == 409) { 
     //handle the exception 
    } 
} 

Answer 2

當Jsoup失敗時，它拋出你不捕捉異常 - 你的代碼只捕獲了一個IOException，但在你的堆棧跟蹤你有一個HttpStatusException。添加第二個catch條款第一catch後：

catch (HttpStatusException e) { 
    if (res1.statusCode == 409) { 
     //handle the exception 
    } 
}